.kua-zu-jian{
    background: #aaaaaa;
    padding: 10px;
    color: white;
    margin-bottom: 5px;
    margin-top: 5px;
}
.kua-zu-jian.a{
    background: #870808;
}
.kua-zu-jian.b{
    background: red;
}
.kua-zu-jian.c{
    background: blue;
}